Cathode ray control apparatus



Get. 8, 1940. HEPP 2,217,409

CATHODE RAY CONTROL APPARATUS Filed Nov. 19, 1937 INVENTOR GERARD H EPP ATTO R N EY Patented Oct. 8, 1940 UNITED STATES PATENT OFFICE CATHODE RAY CONTROL APPARATUS Delaware Application November 19, 1937, Serial No. 175,369 In Germany April 26, 1937 2 Claims.

This invention relates to a deflection coil system for cathode ray tubes in which one or more deflection windings are surrounded by a sheath of conductive material.

Such a sheath may form part of the magnetic circuit in which case it is made from magnetic material and surrounds the whole of the coil system formed by one or more windings or it may constitute an electrostatic screen between the 19 windings of a coil system formed by at least two windings in which case it avoids undesirable couplings between the windings.

A disadvantage concomitant to such a sheath is that eddy currents occur in the sheath and bring about a substantial loss of energy.

For the purpose of avoiding this loss of energy it is suggested according to the invention that the sheath which surrounds one or more deflection coils shouldbe built up from a wire wound 20 to surround this winding or these windings.

In order that the invention may be clearly understood and carried into effect it will now be described more fully with reference to the accompanying drawing, in which Fig. 1 is a cross sectional view of one form of construction of a deflection coil system according to the invention,

Fig. 2 is a perspective view of a magnetic sheath surrounding the deflection coil system shown in Fig. 1.

The deflection coil system shown in. Fig. 1 comprises a vertical deflection coil which, when used a television system, is intended to deflect the 1 cathode ray beam in a direction perpendicular to the scanning lines and is formed by two diametrically opposed deflection coils i and 2. Each l, 2 comprises a number of concentrically wound windings or groups of windings and each group of windings comprises preferably a number of windings. There is in addition a horizontal deflection coil which is constituted by coils H and i2 and which, when used in a television system, may serve to cause the deflecib' tin of the cathode ray beam in a direction pa: iiel to the scanning lines.

The coil system. shown in Fig. 1 contains two coaxially arranged cylinders 3 and 4 made of inlating material, for example fibre. The Vertideflection coils I and 2 are supported by the din" the horizontal deflection coils I! E21 by the cylinder 3. The cylinder 3 or 4 ectively is provided with two right-angled or G respectively which have the function of maintaining the coils H and 12 or I and 2 respectively at the correct relative spacing.

The whole of the coil system is surrounded by a sheath 1 from magnetic material which closes the lines of force and is co-axial with the cylin- 5 ders 3 and 4. The sheath l is made from a wire Wound to surround the coil system, as is shown in Fig. 2, which is a perspective View of the sheath '1. The wire is preferably wound to surround the cylinder 8 of insulating material which 10 surrounds the coils l and 2 and is co-axial with the cylinders 3 and 4. In this case, the cylinder 8 serves not only to support the wire winding but also to avoid a short-circuit of the windings of the coils I and 2. The same result may, however, be obtained when the sheath 1 is constituted by an insulated winding of magnetic material.

The construction shown in Fig. 1 comprises in addition an electrostatic screen 9 arranged between the vertical and the horizontal deflecting coils, said screen avoiding any undesired coupling between the two windings.

According to the invention, this screen is made from a wire wound to surround the coils II and I2 of the horizontal deflection winding and made from conductive non-magnetic material. The losses occurring in the screen 9 are consequently reduced to a minimum. Obviously, the section of the wires by means of which the screen 9 and .the sheath 1 are wound may have any shape desired.

If desired, the inner deflection coil may also have arranged on its inside an electrostatic screen made from wire of conductive non-magnetic material. Such a screen has the function of avoiding electrostatic influence on the electron beam controlled by the coil system, if the tube inside which the electron beam is produced is not provided with a screening layer.

For the purpose of protecting the deflection windings, the ends of the above-described cylindrical coil system are preferably closed by plates of insulating material, for example fibre, which have also secured to them the connecting termi- 4'3 nals for the two deflection windings. These plates are, however, not shown in the drawing since they are not necessary for correct understanding of the invention, which consists in the construction of the sheath 1 and the screen 9.

What I claim is:

1. A coil system for deflecting electronic beams comprising at least a pair of separate coils, an electrostatic sheath interposed between said coils comprising a wire of non-magnetic material Wound so as to electrostatically separate said coils, and a magnetic sheath surrounding said coils comprising a wire of magnetic material continuously Wound to embrace substantially all of the external magnetic field of said coils.

2. Apparatus for deflecting an electron beam in two co-ordinates comprising elctromagnetic means for deflecting the beam in one co-ordinate, a substantially cylindrical form for supporting said electromagnetic means, a second electromagnetic means for deflecting the beam in a direction at right angles to the direction in which it is deflected by said first electromagnetic means, a substantially cylindrical form for supporting said second electromagnetic means, said forms being coaxial, an electrostatic sheath comprising a wire of non-magnetic material wound and positioned between one of said electromagnetic deflecting means and the other of said electromagnetic deflecting means and immediately adjacent one of said supporting forms, and an electromagnetic shield substantially embracing the external magnetic field of said coils comprising a wire of magnetic material wound externally to all of said electromagnetic deflecting means.

GERARD HEPP. 

